Wireless access telecommunications networks (e.g. GSM, UMTS, LTE) have developed tremendously over the past years. In such networks, voice and data services can be provided to terminals having a high mobility, i.e. the terminals move freely through the area covered by the network.
For mobile-terminated calls, i.e. calls made to the mobile terminal, it is essential for the network to locate the terminal in order to set up the connection. To that end, the network has a location management procedure in place.
The telecommunications network is divided into a plurality of location areas (LA). Location areas generally comprise a large number of cells, one or more cells being associated with a base station. The terminal moving through the area keeps the network informed if there is a change of its current location area. However, the knowledge of the location area is generally insufficient for setting up a mobile-terminated call. Thus, prior to setting up a mobile-terminated call, more detailed information about the location of the terminal should be obtained.
As an example, an incoming call request arrives on a gateway mobile switching centre (GMSC) and contains the MSISDN number of the mobile terminal to be contacted. The MSISDN number is used to obtain location information from a Home Location Register (HLR). The HLR uses the MSISDN to identify the address of the Mobile Switching Centre (MSC) currently serving the mobile terminal. The GMSC then uses the MSC address to route the call request to the MSC currently serving the mobile terminal. The MSC determines the location area where the mobile station is registered and sends a message to all base station controllers (BSCs) controlling cells in this location area. The message contains the network identity (TMSI or IMSI) of the mobile terminal and is broadcast in all cells of the location area as a paging message on a paging channel PCH. The mobile terminal regularly (e.g. several times per second) monitors the paging channel PCH and receives the paging message and responds to it when it finds that the TMSI or IMSI in the paging message matches its own TMSI or IMSI. The TMSI or IMSI is known to the terminal; the IMSI is typically stored on the subscriber identity module (SIM) of the mobile terminal.
The mobile terminal generally needs to respond quickly to the paging message, since otherwise the caller may hang up. Therefore, the mobile terminal will respond to the paging message by sending a channel request on a random access channel (RACH). The base station receiving the channel request now knows in which cell the mobile terminal is located and the network assigns radio resources for establishing the connection.
While the above example is based on the establishment of a mobile terminated call in a GSM network, similar steps are taken in other wireless access telecommunications networks, such as UMTS and LTE.
The availability of the above-mentioned wireless access networks has resulted in demands for further services using these networks, including services that relate to so-called machine-type communication (MTC) services. Machine-type communication is currently being standardised in 3GPP, e.g. see TS 22.368. MTC applications typically involve hundreds, thousands or millions of communication modules. Some applications only rarely require access to a telecommunications network. An example involves collecting information by a server from e.g. smart electricity meters at the homes of a large customer base. Other examples include sensors, meters, coffee machines etc. that can be equipped with communication modules that allow for reporting status information to a data processing centre over the telecommunications network. Such devices may also be monitored from a server. The data processing centre may e.g. store the data and/or provide a schedule for maintenance people to repair a machine, meter, sensor etc.